Effect of varying the mitomycin-C treatment area in glaucoma filtration surgery in the rabbit
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M F Cordeiro1, P H Constable, R A Alexander
1Wound Healing Group, Institute of Opthalmology, London, England.
Purpose:
To investigate the effect of varying the treatment area of subconjunctival mitomycin-C (MMC) using an adapted rabbit model of filtration surgery.
Methods:
Twenty-four New Zealand White rabbits underwent filtration surgery, with random allocation to one of three treatments: 5-minute subconjunctival applications of MMC (0.4 mg/ml) with either a large (8 x 10 mm) or small (4 x 2 mm) sponge or no treatment (control). Drainage was achieved by placing an intravenous cannula through a scleral tunnel into the anterior chamber. Rabbits were examined at set intervals for up to 30 days after surgery. Measurements of appearance, size, height, and vascularity of blebs and of intraocular pressure and anterior chamber depth were made by a masked observer. Histologic analysis of eyes was performed at 3, 14, and 30 days.
Results:
Statistical analysis showed a significant difference in bleb survival among all groups (log rank P = 0.0054, with 100% survival with large areas of MMC treatment). Comparison between large and small treatment area groups revealed significant differences in bleb survival (log rank P = 0.0388); bleb area (between-subject analysis, P = 0.009), and bleb height (between-subject analysis, P = 0.005). These differences were seen clinically, with large areas of MMC treatment producing diffuse and elevated blebs, small areas of treatment producing thin-walled and localized blebs with scarring at 21 days, and no treatment resulting in comparatively vascularized and scarred blebs before 14 days. Histologic analysis revealed clear differences among groups, with an increase in subconjunctival cellularity and scar tissue in eyes with failed blebs.
Conclusions:
The size of the area of subconjunctival MMC treatment significantly affects surgical outcome. Histologic features mirror differences observed clinically. Alteration of the size of the MMC treatment area may provide an alternative and more controllable approach to modulating the wound-healing response after drainage surgery and, more important in the clinical context, to modifying bleb morphology.
Insights
Varying the treatment area of subconjunctival mitomycin-C (MMC) after filtration surgery significantly impacts bleb survival and morphology. Larger treatment areas improve bleb survival and reduce scarring, offering a controllable method for modulating wound healing.
Area of Science:
- Ophthalmology
- Surgical Innovation
- Wound Healing Research
Background:
- Filtration surgery is a common procedure for managing glaucoma.
- Subconjunctival mitomycin-C (MMC) is used to enhance filtration surgery outcomes.
- Optimizing MMC application is crucial for preventing scarring and improving bleb function.
Purpose of the Study:
- To investigate how different subconjunctival mitomycin-C (MMC) treatment areas affect outcomes in a rabbit model of filtration surgery.
- To determine the optimal application size of MMC for successful filtration surgery.
Main Methods:
- New Zealand White rabbits underwent filtration surgery and were randomized to receive subconjunctival MMC (0.4 mg/ml) with a large (8x10 mm) or small (4x2 mm) sponge, or no treatment (control).
- Bleb appearance, size, height, vascularity, intraocular pressure, and anterior chamber depth were monitored for 30 days.
- Histologic analysis was performed at 3, 14, and 30 days post-surgery.
Main Results:
- A significant difference in bleb survival was observed among groups (P=0.0054), with 100% survival in the large MMC treatment group.
- Large MMC areas resulted in diffuse, elevated blebs, while small areas led to thin-walled, localized blebs and scarring.
- Histologic analysis showed increased subconjunctival cellularity and scar tissue in eyes with failed blebs.
Conclusions:
- The size of the subconjunctival MMC treatment area significantly influences the success of filtration surgery.
- Modifying the MMC application area provides a controllable method to modulate wound healing and bleb morphology.
- This approach may offer a more effective strategy for improving surgical outcomes in glaucoma patients.